(1) Field
The present invention relates generally to heating water using solar energy and, more particularly, to an absorber formed from two identical halves of darkened glass that are fused together.
(2) Related Art
Small-scale solar water heating systems are typically constructed of an insulating housing, including a window which permits solar radiation to enter the housing, and a solar collector. Solar collectors are also known as “absorbers”. Solar water heaters are generally categorized as active or passive. Active heaters pump water from a reservoir, such as a tank or pool, to the solar collector where the water is heated, then onto the desired destination. These systems require various controllers, including water flow controllers, since a relatively small volume of water resides in the solar collector, and this water, if overheated, could easily damage or destroy the delicate collector. Pool heaters and flat panel water heaters commonly seen on roofs are usually active solar heaters. As of the date of filing this application, a typical active solar water heater designed to meet most of the water heating the needs of a family of four costs approximately $7,000US to $9,000US fully installed in the US. In the San Francisco Bay Area, the annual energy expenditure for “conventionally” heating water for a family of four is approximately $400US.
Passive water heaters are generally less structurally sophisticated insofar as they lack pumping and precise water flow controllers. Instead, water is moved via the thermosiphoning effect through a large solar collector which also serves as a storage tank, then onto the desired location. A very simple version of this is found in many tropical locations, such as southern China, where uninsulated black tanks are often placed on roofs to simultaneously store and heat water. Without insulation, however, the hot water must be consumed during the solar day. As of the filing date of this application, more sophisticated passive water heaters, which are generally capable meeting heated water needs of a family of four in the US, cost approximately $7,000US installed in the Bay Area.
Many potential consumers consider solar heating systems to be cost prohibitive. This hurdle to ownership is compounded because the projected financial break-even point for solar heating systems is in the decades. Accordingly, solar heating systems are generally considered to be environmentally friendly but financially unfriendly investments. This is unfortunate given the myriad of problems associated with the consumption of non-renewable energy sources.
Copper is widely considered the material of choice in solar water heating systems. It is bendable, can be soldered and brazed, undergoes minimal corrosion, and does not pose water-related toxicity concerns. However, copper is quite expensive, trading as a commodity in the $2.00 to $4.00US range in the three years prior to filing this application. In short, the cost of copper is a major hurdle to solar heating system ownership for many consumers. In some solar heaters, aluminum may be used in place of part of the copper to reduce cost, but this adds substantially to assembly costs. The other major cost contributor to solar heating systems is the labor associated with manufacturing. Typically systems include a multitude of delicate parts that must be assembled with precision because sloppy assembly will lead to leaks and system failure.
Thus, there remains a need for a new and improved solar water heating system that is economically feasible for consumers. Ideally this system would be relatively simple and inexpensive to manufacture, be constructed of environmentally friendly and inexpensive materials, and not be any more difficult to install than already known solar water heating systems. This new and improved solar water heating system should also perform as well as current systems with respect to temperature and availability of water, longevity of system and aesthetics.